L1 bulbs have a hole in the base which allows it to fit designated L1 fittings as well as standard GU10 fittings however L1 fittings are designed not to accept standard GU10 bulbs. This is to ensure compliance with Building Regulation L1.

L1 bulbs have a hole in the base which allows it to fit designated L1 fittings as well as standard GU10 fittings however L1 fittings are designed not to accept standard GU10 bulbs. This is to ensure compliance with Building Regulation L1.